Work vehicles typically have internal combustion engines that emit hot exhaust gases. In recent years, exhaust gas temperatures have increased due to the use of catalytic devices. These devices improve the combustion of internal conventions by using catalysis to oxidize residual combustibles in the flow of exhaust gas leaving the internal combustion engine.
In a first arrangement, shown in U.S. Pat. No. 3,875,745, exhaust gas leaving an internal combustion engine is directed into a chamber that encloses a venturi. The exhaust gas flow is reversed in direction of flow two or three times and is injected into a narrow annular gap. Ambient air is drawn into an open inlet and is carried straight to the venturi by the exhaust gas flow, thereby mixing the hot exhaust gas with much cooler ambient air before the mixture is released into the atmosphere.
A problem with this arrangement is the need to redirect the exhaust gas flow at right angles (several times) and the need to pressurize the exhaust gas surrounding the venturi. This increase in pressure builds up back pressure in the exhaust pipe thereby reducing engine efficiency.
In another arrangement, shown in US2007/0245725 (A1), a dual-stage venturi exhaust cooling device is shown. In this arrangement, exhaust gas flow through the cooler is essentially linear, flowing in a straight line from entrance to exit, thereby reducing the significant back pressure generated by the arrangement of U.S. Pat. No. 3,875,745.
In a first stage of the '725 arrangement, exhaust gases introduced into an elongate tubular structure in a first direction are split to form a ring of exhaust gas. Ambient air is introduced into the exhaust gas ring immediately downstream of the venturi. In a second stage of the '725 arrangement, the mixed exhaust gas and ambient air is channeled into an elongate tube fixed to the end of the venturi. This elongate tube has several apertures disposed along its length into which ambient air is sucked. This arrangement limits the amount of cooling air that can be added in the second stage and induces turbulence and drag from the many discrete punctures in the sidewall.
What is needed is an improved exhaust cooler that avoids the limitations of the prior art by supplying a greater flow of cooling air to mix with the exhaust while providing less drag.